I'll have to agree with Brett; there are many other things you can do in this hobby that would fill you with a greater sense of accomplishment for far less money and/or aggravation (custom winding an output transformer or building a line-level preamp both spring to mind).

Just in case nobody has mentioned it, try to attend a local hamfest. I've picked up 10 A variacs fused and in housings for as little as $5 - and I can assure you they're FAR safer and more reliable than anything you can build.

Here is a possible compromise answer :
Buy one of the cheap readily available variacs, you will have a good safe one, as Brett and Zman3 suggest,
then
copy it, and your desire for a sense of accomplishment will be satisfied.

I didn't mean to rain on anyone's parade, but for the same effort you could wind your own audio transformers which will teach you more and you'll get a lot more use out of. I use my variac a bit, and on a busy week it'd be lucky to get an hours use.

Thanks for the input. Winding trannies is on my accomplishment list, but I don't think I'm quite ready for it yet...baby steps first. I'm kind of a Rube Goldberg-type, so anything is gratifying to me. With the clunkers I have around, a variac will get quite a workout in my laboratory.

Any recomendations? I just picked up one as a part of a test equipment buy. It looks to be from the 30's,and the cord appears to have caught fire! I'm guessing I shoud just junk it. I'd like something newish and cheap.